After how many minutes of exposure to fire can unprotected engineered steel and wooden trusses fail?

Unprotected engineered steel and wooden trusses are particularly vulnerable in the event of a fire due to their composition and structural characteristics. When exposed to elevated temperatures, these materials begin to lose their strength and integrity. The correct timing for failure can vary based on several factors, including the intensity of the fire, the moisture content of the wood, and the design of the trusses.

Typically, unprotected wooden trusses can fail within a critical time frame of 5 to 10 minutes when subjected to fire conditions. The wood components start to char and weaken, while the engineered steel trusses, although initially capable of withstanding more heat, will begin to lose their load-bearing capacity as temperatures rise beyond their threshold. It is important for fire service personnel to understand this timeline to make effective decisions regarding fire suppression and evacuation strategies, ensuring safety during operations.

The other options suggest either a shorter or longer time frame, which does not align with the established understanding of fire dynamics affecting these materials. Therefore, knowing that most failures happen within the 5 to 10 minute range helps ensure better preparedness and response in fire scenarios.